This invention relates to a cylindrical, blow-molded lidded barrel (wide-mouthed drum) with a barrel lid and tension-ring closure, in which in the closed position, the tension ring, which is U-shaped in cross section, engages with its upper leg over the outside upper edge of the lid and engages with its lower leg under an outside edge of the barrel that runs basically horizontally or slightly obliquely downward in the opening area of the body of the barrel.
Such a lidded barrel is known from, e.g., DE-B-41 08 606. In the case of this barrel, however, the tension-ring closure is arranged some distance below the upper edge of the lid or the opening of the barrel, so that handling such a filled, e.g., 220-liter lidded barrel with a shipping weight of about 230 kg is possible only using special barrel-gripping tools. This type of a lidded barrel was developed by Mauser in 1975 and distributed worldwide under the designation “standard lidded barrel”; it is well-suited for handling solid, particulate or pasty contents, but such a barrel is not readily suited for use with liquids.
In the case of lidded barrels, the sealing action of the barrel lid on the barrel mouth is produced by bringing about axial prestressing on the lid seal via the tension ring leg bevels at the upper edge of the lid and at the outer border of the barrel body (or indentation) as the tension ring is clamped or closed.
On lidded barrels that are approved for use in, e.g., the chemical industry, certain requirements with respect to their storage and transport safety are set; compliance with these requirements is tested and examined in special acceptance tests (e.g., dropping on its side, jacket dropping, diagonal dropping on the edge of the lid, static internal pressure test, i.a.). In the case of known existing plastic lidded barrels, even when barrels are dropped from heights of about 1.20 m—e.g., from the bed of a truck—leaks occur, especially in the case of liquids, or complete detachment of the barrel lid can even occur.
The drawbacks of previously known lidded barrels consist of, especially,
a) when there is axial internal pressure on the barrel lid (surge pressure when a barrel filled with water is dropped on its jacket or when there is hydraulic internal pressure in a closed barrel),
b) when a closed barrel that is filled with water slams flat against a side wall (jacket dropping), and
c) when a closed barrel that is filled with water drops diagonally onto the edge of the lid, various reactions occur:                the barrel lid is pressed axially outward,        the tension ring is pulled axially outward,        the tension ring (together with lid and barrel mouth area) is flattened at the central impact point,        the tension ring is heavily buckled laterally at the impact point and its U-shape is flared at both buckling points,        the lid edge tries to slide out from under the upper tension ring leg,        prestressing on the seal is reduced and the locking system begins leaking.        
The stresses that occur with the deformations must be absorbed in each case by the U-shaped tension ring. In this connection, the legs are pressed outward (flared) in the buckling areas. If the stress on the legs is too high, it leads to permanent deformations, prestressing on the seal is reduced at those points, and significant flaring results in leaks or leaking of the barrel.
An attempt is thus to be made to reduce the deformation of the tension ring, especially the flaring in the U-area, by structural measures, especially in the barrel mouth area, at the barrel lid and/or tension ring, while at the same time continuing to ensure good handling, i.e., easy closing of the tension ring.